<?php

  class databases{
   public $user = 'luoqifnag';
      public function __construct(){
         $this->$a = 'oop';
      }
      
      public function show(){
          echo $this->$a;
      }
      
      public function te(){
          global $user;
          $user = 'ppppp';
          echo $user;
      }
      
      public function tee($username = 'nihao'){
          /* global $user;
         echo $user; */
          echo $username.'=======================================';
          
      }
  }
  
  
  
  
  $d = new databases();
  $d->te();
  $d->tee();
  var_dump($GLOBALS);
  